Movement and interaction within the environment requires a subject to sense the environment using visual, audio, and other sensory processes, as well as sense her/his body position and movement. The sensory, cognitive, and motor processes required are normally performed with speed and accuracy. However, when an individual suffers a brain injury from trauma, stroke, or the like, there can be a broad range of sensory, motor, and/or cognitive functions that are impaired (Teasell et al., 2003), reducing the individual's ability to move and interact within the environment. This leads to a substantive impact on the individuals' ability to perform daily activities.
Clinical assessment plays a crucial role in all facets of patient care, from diagnosing a specific disease or injury, to management and monitoring of therapeutic or rehabilitation strategies to ameliorate dysfunction (Van Dursen and Brent, 1997). Medicine relies on a breadth of technologies and tests to quantify the function of various organ systems that has radically changed the process of diagnosing disease. However, the ability to assess the function of the brain, particularly sensory, motor, and cognitive functions, is surprisingly limited and continues to be based largely on subjective estimates of performance. For example, assessing the ability of a patient to touch their nose and a clinician's finger repeatedly based on a score of 0, 1, or 2. Such subjective rating systems are necessarily coarse to ensure reliability and validity, but such coarseness makes it difficult to detect subtle changes in sensorimotor function. Furthermore, subtle impairments such as small delays in reacting or increases in movement variability cannot be identified easily from visual inspection. Evidence-based reviews of stroke rehabilitation recommend sensorimotor assessments based on ordinal scales. The most reliable of such scales have relatively coarse rating systems, reflecting that it is difficult for even an experienced observer to discriminate small changes in performance using only the naked eye.
A number of pen and paper tasks have been developed to quantify cognitive processes. However, such tasks often do not consider the speed of a subject's ability to complete a task and therefore may be limited in their effectiveness as a tool to assess cognitive processes essential for everyday activites.
Automated processes have been developed such as computer based assessments. For example, CANTAB provides a range of specialized tasks to assess various aspects of cognitive function by having subjects use one of their limbs to contact and interact with a computer screen. Devices such as Dynavision may be used to quantify how subjects respond to stimuli across a large portion of the workspace by recording the reaction time for the subject to hit various targets that are illuminated at random times. Various technologies have also been developed to quantify limb movement, such as robots that can quantify the ability of subjects to make visually guided reaching movements (e.g., KINARM, U.S. Pat. No. 6,155,993 issued 5 Dec. 2000 to Scott).
While such technologies provide a range of information on sensorimotor performance, they lack the ability to assess several key aspects of normal sensorimotor and cognitive function that are crucial for performing daily activities. For example, the decision to reach for an object requires one to decide which limb to use. In many cases, the selection is based on the proximity of the object, the ongoing action of each limb along with general preferences for using one limb over the other for certain tasks (hand preference). Brain injuries are often asymmetric with greater impairments in sensory or motor functions for one side of the body as compared to the other. This may affect how an individual with a brain injury chooses one limb versus the other to perform a task.
A further effect of brain injury may be the subject's inability to respond to or interact with parts of her/his workspace. For example, a subject with a lesion involving the right parietal cortex may have difficulty responding to objects in the left part of the workspace. Traditional pen and paper tasks such as the Behavioural Inattention Test (BIT) may be used to quantify this deficit. However, because a time limit is usually not imposed on subjects performing this task and only a small region of the workspace sampled (i.e., the size of paper used), the test is of limited ability to quantify impairments in this domain.